Texas Instruments MULTIPLE MODE SYNCHRONOUS DC/DC CONTROLLER TPS5103EVM-136 TPS5103EVM-136 Datenbogen

SLVS240A – SEPTEMBER 1999 – REVISED MAY 2001

5

POST OFFICE BOX 655303 

•

 DALLAS, TEXAS 75265

SOFTSTART sets the sequencing of the output for any possibility. The capacitor value for a start-up time can
be calculated by the following equation:

C = 2 x T (

µ

F)

Where C is the external capacitor value, and T is the required start-up time in (ms).

The controller can be switched into the standby mode by grounding the STBY terminal. When it is in standby
mode, the quiescent current is less than 1.0 

µ

A.

The under-voltage lockout (ULVO) threshold is approximately 3.8 V. The typical hysteresis is 55 mV.

If the internal 5-V switch senses a 5-V input from REG5V, the internal 5-V linear regulator will be disconnected
from the MOSFET drivers. The external 5 V will be used for both the low-side driver and the high-side bootstrap,
thus, increasing the efficiency.

The PWM/SKIP switch selects the output operating mode. This controller has three operational modes, PWM,
SKIP, and hysteretic. The PWM and SKIP mode control should be used for slower-transient applications.

The oscillator gives a triangle wave by connecting an external resistor to R

T

 and an external capacitor to C

T

.

The voltage amplitude is 0.43 V ~ 1.17 V. This wave is connected to the noninverting input of the PWM
comparator.

Frequency

Fixed

Not fixed

Transient response

Normal

Very fast

Feed back compensation

Need

Needless